Home / Digital SAT Math Practice Questions – Advanced : Systems of two linear equations in two variables

Digital SAT Math Practice Questions – Advanced : Systems of two linear equations in two variables

DSAT MAth Practice questions – all topics

  • Algebra Weightage: 35%  Questions: 13-15
    • Linear equations in one variable
    • Linear equations in two variables
    • Linear functions
    • Systems of two linear equations in two variables
    • Linear inequalities in one or two variables

DSAT MAth and English  – full syllabus practice tests

Question Hard

\[ \begin{aligned} & -8x – 24 = 10y \\ & 15y = 6 – 18x \end{aligned} \]

The solution to the given system of equations is \((x, y)\). What is the value of \(x\) ?

A) 3

B) 5

C) 7

D) 9

▶️ Answer/Explanation with Desmos
Solution

Answer: 7

Question   Hard

2x-2y=2

One of the two linear equations in a system is given. The system has exactly one solution. Which equation could be the second equation in this system?

A. -8x+8y =- 3

B. 3x-3y=8

C. -10x+8y=5

D. -x+y =- 1

▶️Answer/Explanation

Answer: C

A consistent system is considered to be an independent system if it has a single solution. This means that the two lines have different slopes and intersect at one point in the plane. \(y\)-intercept.
The slope of the given equation is \(-\dfrac{-2}{2}=1\).
The slope of option A is \(-\dfrac{8}{-8}=1\).
The slope of option B is \(-\dfrac{-3}{3}=1\).
The slope of option C is \(-\dfrac{8}{-10}=\dfrac{4}{5}\).
The slope of option D is \(-\dfrac{1}{-1}=1\).

▶️Desmos



  Question  Hard

One of the two linear equations in a system is −6𝑥 + 7𝑦 = −6. The system has no solution. Which equation could be the second equation in this system?

A. 6𝑥 − 7𝑦 = 0
B. \(-\frac{21x}{4}+\frac{49y}{8}=-\frac{21}{4}\)
C. \(-\frac{21x}{4}-14y=0\)
D. 6𝑥 − 7𝑦 = 6

▶️Answer/Explanation

Answer: A

If the system of equations has no solution, then their slopes are equal and \(y\)-intercept are not equal. The lines are parallel.
The slope of the given line is \(-\dfrac{7}{-6}=\dfrac{7}{6}\).
The \(y\)-intercept of the given line is \(\dfrac{-6}{-6}=1\).
The slope of option A is \(-\dfrac{-7}{6}=\dfrac{7}{6}\).
The \(y\)-intercpt of option A is \(0\).
The slope of option B is \(-\dfrac{\dfrac{49}{8}}{\dfrac{-21}{4}}=\dfrac{7}{6}\).
The \(y\)-intercept of option B is \(\dfrac{\dfrac{-21}{4}}{\dfrac{-21}{4}}=1\)
The slope of option C is \(-\dfrac{-14}{\dfrac{-21}{4}}=\dfrac{8}{3}\)
The \(y\)-intercept of option C is \(\0\)
The slope of option D is \(-\dfrac{-7}{6}=\dfrac{7}{6}\)
The \(y\)-intercept of option D is \(\dfrac{6}{6}=1\)

▶️Desmos

Question Hard

\(-3x + 4y = 4\)

\(4x – 3y = 0.5\)

The solution to the given system of equations is the ordered pair \((x, y)\). What is the value of \(y\)?

A) 1.5

B) 2.0

C) 2.5

D) 3.0

▶️ Answer/Explanation with Desmos
Solution

Answer: 2.5

Question Hard

\[ \begin{aligned} & y = \frac{3}{2} x – \frac{1}{2} \\ & y = \frac{k}{3} x + \frac{1}{3} \end{aligned} \]

In the system of equations above, \(k\) is a constant. If the system has no solutions, what is the value of \(k\) ?

A) 2.0

B) 3.0

C) 4.5

D) 6.0

▶️ Answer/Explanation
Solution

Answer: 4.5 or \(\frac{9}{2}\)

For no solution, slopes must be equal: \(\frac{3}{2} = \frac{k}{3}\). Solving for \(k\), \(k = \frac{9}{2} = 4.5\).

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